Game of Thrones creators David Benioff and D.B. Weiss' newly greenlit HBO series about an alternative history were slavery was never abolished in America has received much criticism online.

HBO granted a series order to the project, entitled Confederate, a new drama from the duo behind the hit fantasy drama Game of Thrones, which is currently airing its penultimate season.

Confederate will chronicle the events leading to the Third American Civil War and will take place in an alternative historical timeline where the southern states seceded from the Union, leading to slavery evolving into a modern institution.

Weiss and Benioff will act as showrunners, executive producers and writers on the project, with production to begin after Game of Thrones concludes.

"We have discussed Confederate for years, originally as a concept for a feature film," Weiss and Benioff said in a joint statement.

"But our experience on Thrones has convinced us that no one provides a bigger, better storytelling canvas than HBO. There won’t be dragons or White Walkers in this series, but we are creating a world."

Many Twitter users have voiced their concern about the premise of the show with some users labelling it as a "horrible idea", "just wrong" and "harmful".

Other users have come out in support of the idea with some likening it to the Amazon series Man in the High Castle, which takes place in an alternative history where World War II had a different outcome.